hypoplastron


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hypoplastron

[¦hī·pō¦plas·trən]
(vertebrate zoology)
Either of the third pair of lateral bony plates in the plastron of most turtles.
References in periodicals archive ?
ROM-42102 is a fragment of the right hypoplastron. On its ventral surface, this specimen exhibits a well-preserved abdominal-femoral sulcus (Fig.
(A-B) ROM-41848 left epiplastron in ventral view; (C-D) ROM-42183 entoplastron in ventral view; (E-F) ROM-42070 right epiplastron in ventral view; (G-H) ROM-42114 right hyoplastron in ventral view; (I-J) ROM-42102 right hypoplastron in ventral view; (K-L) ROM-42053 right xiphiplastron in ventral view; (M-N) ROM 42056 left xiphiplastron in ventral view; (O) plastron of extant Rhinoclemmys melanosterna CRI-4898 in ventral view.
-- The hypoplastron of Emydoidea blandingii is easily distinguished from those of other North American emydid turtles of similar size on the basis of the following characteristics: 1) abdominal-pectoral sulcus joins hyo-hypoplastral suture at midline; 2) humeral-pectoral sulcus placed far anteriorly; 3) angular epi-hypoplastral suture; 4) bridge buttress limited in its anterior extent; and 5) posterior edge of bone lateral to bridge buttress bevelled for hypoplastral hinge attachment.
Five shell specimens appear to correspond to fragments of the hyoplastron or hypoplastron and fragments of the costal elements (figure 2 a-e).
Plastron plates: epiplastrals = epi, entoplastron = ento, hyoplastron = hyo, hypoplastron = hypo, xiphiplastron = xiphi.
with the insertion of inguinal buttress (plate 3, figures 3-4); PMUL HS 384a-c-A10.02.04, three hyo or hypoplastron remains from the bridge region; PMUL HS 387a-c-A10.02.04, two pleural remains, one peripheral plate lost the marginal border; PMUL HS 385a-A10.02.04, one hexagonal neural 6A broader than long (1,6 time).
Description: The most characteristic shell element in the present material is the hypoplastron remain dex.
Description of holotype: Most parts of the posterior carapace area including neurals IV to VIII, pleurals III to VIII, right free costae III to VIII, left free costae V to VIII, right peripheral edge, single parts of left peripherals, left pubis, left coracoid and the right lateral wings of hyoplastron and hypoplastron.